Conventional devices maneuver a vehicle using maneuvering moves, which term may concern forwards maneuvering moves and/or backwards maneuvering moves. The maneuvering moves include at least one trajectory, along which the vehicle is movable. The trajectories in question describe continuous paths along which the vehicle is guided. These may concern circular paths, but the trajectories are also able to deviate from basic mathematical geometries. In particular, the maneuvering moves in question may also have sections that run along a straight line. If, for instance, a vehicle is being maneuvered into a parking space, the driver may first guide the vehicle past the parking space, which may be done along a straight line or a first trajectory. A second trajectory following this first trajectory may be determined by the device in such a way that the vehicle is able to get into the parking space. The number of trajectories is not limited, in this context, and, depending on the driving situation, one, two or more trajectories may be required.
Basically there is the possibility of executing the trajectories as circular paths that are guided into one another at a stop point. If the vehicle is maneuvering on the first circular path in forward travel, when there is a reversal of the travel direction, the second circular path of the vehicle, having backwards travel, may be driven, starting from the stop point. However, this often brings up the disadvantage that the driver, during standstill in the stop point, has to make a steering motion, whereby the vehicle has to be stopped for a certain time in the stop point. The stop point may lie, for instance, in the area of oncoming traffic, so that a dangerous situation is created during the parking process. Based on the frictional grip between the tire and the road, the tires are subject to greater wear, and steering for the steering motion has to be performed using greater force, which is perceived as being less comfortable.
A method for semiautonomous steering of a vehicle parking backwards into a parking space is described in German Patent No. DE 102 56 770 A1, in which one trajectory for parking is subdivided into four curve sections, and in this context, the curve sections extend by one circular arc section or a clothoid section. At the beginning of the parking process, the vehicle may stand at any desired angle transversely to the longitudinal direction of the parking space, and, using a measuring electronics system, the position and the alignment of the vehicle relative to the parking space in the initial position is detected. The first curve section, in this context, may describe a straight line or a clothoid, it being the case that the first curve section transits smoothly into the second curve section. In the final analysis, a parking process comes about via which, between the initial position and the parked position of the parking process, the steering is controlled in such a way that the steering angle changes are continuous. This has the advantage that, during the parking process, the vehicle does not have to be stopped at the transitions between the individual curve sections, but is able to be driven without stopping from the starting position to the parked position. The use of the clothoids described, however, relates only to maneuvering moves which are defined in a continual direction of motion of the vehicle, so that between the curve moves steering motions of the vehicle are required which may possibly have to be executed by the driver.
A parking assistance is described in German Patent Application No. DE 10 2005 006 966, by which a steering torque is applied to the steering wheel of the motor vehicle, and at least one artificial steering stop is generated, so that the driver is guided by the artificial steering stop on a drive-in path for parking the vehicle. To do this, at least a subsection of the drive-in path is ascertained based on one or more polynomials. For vehicles standing far removed from the parking space, the starting point to the drive-in path is preferably selected to be in the vicinity of a deflection point, because a flat entering path brings with it a direct path and only a slight amount of driving into an oncoming traffic lane. This does, however, achieve the advantage that as great as possible a starting range for the parking process is produced, so as to avoid unnecessary steering processes. Nevertheless, the parking assistance requires steering maneuvers that are necessary between two parking moves.